Re-Transmitting a Poll to a Peer Protocol Entity When a Timer Expires

1. A method, comprising: transmitting, by a protocol entity, a poll to a peer protocol entity to trigger status reporting at the peer protocol entity; starting a timer with a duration based on whether at least one predefined condition is met, wherein the at least one predefined condition depends at least on a difference between a value of a sequence number (SN) of a protocol data unit (PDU) in which the poll is transmitted and a value of a lowest sequence number (SN) for which neither acknowledgement or non-acknowledgement has been received; and re-transmitting a poll when the timer expires.

2. The method according to claim 1 , further comprising receiving an acknowledgement (ACK) or non-acknowledgement (NACK) from the peer protocol entity.

4. The method according to claim 1 , wherein, after transmitting the poll, the protocol entity's transmission buffers become empty.

5. The method according to claim 1 , wherein, when, for the sequence number (SN) of a data protocol data unit (PDU) in which the poll is transmitted, SN−NEW_STATE_VARIABLE≥3, the method further comprising setting a next duration of the poll re-transmit timer to a time configured by radio resource control (RRC), wherein NEW_STATE_VARIABLE is a variable storing a value of the sequence number (SN) of a next acknowledged mode data (AMD) protocol data unit (PDU) for which any initial positive or negative acknowledgement is to be received.

6. The method according to claim 5 , wherein, when SN−NEW_STATE_VARIABLE≥1, the method further comprising setting a next duration of the timer to a time configured by radio resource control (RRC) multiplied by ¾.

7. The method according to claim 6 , wherein, when SN−NEW_STATE_VARIABLE is not greater than or equal to 1, the method further comprising setting a next duration of the timer to a time configured by radio resource control (RRC) divided by 2.

8. The method according to claim 1 , wherein the protocol entity comprises an acknowledged mode (AM) radio link control (RLC) entity, and wherein the timer comprises a poll re-transmit timer.

9. An apparatus, comprising: at least one processor; and at least one memory including computer program code, wherein the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to transmit a poll to a peer protocol entity to trigger status reporting at the peer protocol entity; start a timer with a duration based on whether at least one predefined condition is met, wherein the at least one predefined condition depends at least on a difference between a value of a sequence number (SN) of a protocol data unit (PDU) in which the poll is transmitted and a value of a lowest sequence number (SN) for which neither acknowledgement or non-acknowledgement has been received; and re-transmit a poll when the timer expires.

10. The apparatus according to claim 9 , wherein the at least one memory and computer program code are further configured, with the at least one processor, to cause the apparatus at least to receive an acknowledgement (ACK) or non-acknowledgement (NACK) from the peer protocol entity.

12. The apparatus according to claim 9 , wherein, after transmitting the poll, transmission buffers of the apparatus become empty.

13. The apparatus according to claim 9 , wherein, when, for the sequence number (SN) of a data protocol data unit (PDU) in which the poll is transmitted, SN−NEW_STATE_VARIABLE≥3, the at least one memory and computer program code are further configured, with the at least one processor, to cause the apparatus at least to set a next duration of the poll re-transmit timer to a time configured by radio resource control (RRC), wherein NEW_STATE_VARIABLE is a variable storing a value of the sequence number (SN) of a next acknowledged mode data (AMD) protocol data unit (PDU) for which any initial positive or negative acknowledgement is to be received.

14. The apparatus according to claim 13 , wherein, when SN−NEW_STATE_VARIABLE≥1, the at least one memory and computer program code are further configured, with the at least one processor, to cause the apparatus at least to set a next duration of the timer to a time configured by radio resource control (RRC) multiplied by ¾.

15. The apparatus according to claim 14 , wherein, when SN−NEW_STATE_VARIABLE is not greater than or equal to 1, the at least one memory and computer program code are further configured, with the at least one processor, to cause the apparatus at least to set a next duration of the timer to a time configured by radio resource control (RRC) divided by 2.

16. The apparatus according to claim 8 , wherein the apparatus comprises an acknowledged mode (AM) radio link control (RLC) entity, and wherein the timer comprises a poll re-transmit timer.

17. A computer program, embodied on a non-transitory computer readable medium, the computer program configured to control a processor to perform a process, comprising: transmitting a poll to a peer protocol entity to trigger status reporting at the peer protocol entity; starting a timer with a duration that is based on whether at least one predefined condition is met, wherein the at least one predefined condition depends at least on a difference between a value of a sequence number (SN) of a protocol data unit (PDN) in which the poll is transmitted and a value of a lowest sequence number (SN) for which neither acknowledgement or non-acknowledgement has been received; and re-transmitting a poll when the timer expires.